Device for conveying flat objects with a synchronization system

Abstract

A device for conveying flat objects in series and edge-on, in which the flat objects ( 12 ) are moved in a conveying direction (D), while at the same time being separated each from the next by a spacing which is normally constant, has a synchronization system ( 2 ) capable of compensating for any variations in spacing between two consecutive objects. The system includes two parallel rows ( 3, 4 ) of driven wheels ( 3 A- 4 C) made of elastically deformable elastomer and between which each object is gripped and moved in the conveying direction. Each wheel has a rotation spindle ( 6 ), the position of which is fixed, and the wheels are rotated by a motorization system which is controlled to accelerate and/or retard the movement of each object between the two rows of wheels on the basis of a detection whether the front edge of the object has been early or late in passing a determined position upstream of the two rows of wheels compared with a time reference indicating the spacing between objects. The device may be used in a postal sorting machine operating in a synchronous mode.

What is claimed is:  
     
       1. A device for conveying flat objects in series and edge-on, in which said flat objects are moved in a conveying direction while at the same time being separated each from the next by a spacing which is normally constant, which device further comprises a synchronization system capable of compensating for any variations in spacing between two consecutive objects, wherein this system further comprises two parallel rows of driven wheels made of elastically deformable elastomer and between which each object is gripped and moved in said conveying direction, each wheel having a rotation spindle, the position of which is fixed, each fixed-position rotation spindle comprising two twin wheels, the wheels of the two rows of wheels located upstream in the direction of conveying extending over a shorter height than the wheels located downstream, and the wheels being rotated by a motorization system which is controlled to accelerate and/or retard the movement of each object between the two rows of wheels on the basis of a detection as to whether the front edge of the object has been early or late in passing a determined position upstream of the two rows of wheels, compared with a time reference which indicates the spacing between objects. 
     
     
       2. The device as claimed in  claim 1 , comprising a first sensor disposed close to the upstream wheels of the two rows of wheels in the conveying direction and arranged to detect the passage of the front edge of each flat object, and a second sensor disposed close to the downstream wheels of the two rows of wheels in the conveying direction and arranged to detect the passage of the rear edge of each flat object, and in which, in response to detection by the first sensor, the motorization system is controlled to accelerate and/or retard the movement of the flat object between the two rows of wheels to a certain conveying speed and in which, in response to detection by the second sensor, the motorization system is controlled to pick up a subsequent object between the two rows of wheels at a certain speed which is lower than said conveying speed, and in which if first said sensor detects the passage of the front edge of a flat object which is delayed with respect to said time reference, the motorization system is controlled to accelerate and then retard the movement of the flat object between the two rows of wheels until said certain conveying speed is reached. 
     
     
       3. The device as claimed in  claim 1 , in which the two rows of wheels extend over a length in said conveying direction which is slightly longer than the longest length of a flat object. 
     
     
       4. The device as claimed in  claim 1 , in which said synchronization system has a first wheel in one of said two rows of wheels and a second wheel in the other of said two rows of wheels, said first wheel being in contact with said second wheel, and wherein said first wheel has a hardness which is slightly greater than the hardness of said second wheel. 
     
     
       5. A device for conveying flat objects in series and edge-on, in which said flat objects are moved in a conveying direction while at the same time being separated each from the next by a spacing which is normally constant, which device further comprises a synchronization system capable of compensating for any variations in spacing between two consecutive objects, wherein this system further comprises two parallel rows of driven wheels made of elastically deformable elastomer and between which each object is gripped and moved in said conveying direction, each wheel having a rotation spindle, the position of which is fixed, the wheels being rotated by a motorization system which is controlled to accelerate and/or retard the movement of each object between the two rows of wheels on the basis of a detection as to whether the front edge of the object has been early or late in passing a determined position upstream of the two rows of wheels, compared with a time reference which indicates the spacing between objects, and in which each wheel comprises a hub and an annular tread strip connected to the hub by elastically deformable circular arc-shaped fins, the two ends of each fin which are for connecting to the hub and to the annular tread strip of the wheel being disposed along a common radius of the wheel. 
     
     
       6. The device as claimed in  claim 5 , comprising two twin wheels on each fixed-position rotation spindle, and in which the wheels of the two rows of wheels located upstream in the direction of conveying extend over a shorter height than the wheels located downstream. 
     
     
       7. The device as claimed in  claim 5 , comprising a first sensor disposed close to the upstream wheels of the two rows of wheels in the conveying direction and arranged to detect the passage of the front edge of each flat object, and a second sensor disposed close to the downstream wheels of the two rows of wheels in the conveying direction and arranged to detect the passage of the rear edge of each flat object, and in which, in response to detection by the first sensor, the motorization system is controlled to accelerate and/or retard the movement of the flat object between the two rows of wheels to a certain conveying speed and in which, in response to detection by the second sensor, the motorization system is controlled to pick up a subsequent object between the two rows of wheels at a certain speed which is lower than said conveying speed, and in which if first said sensor detects the passage of the front edge of a flat object which is delayed with respect to said time reference, the motorization system is controlled to accelerate and then retard the movement of the flat object between the two rows of wheels until said certain conveying speed is reached. 
     
     
       8. The device as claimed in  claim 5 , in which the two rows of wheels extend over a length in said conveying direction which is slightly longer than the longest length of a flat object. 
     
     
       9. The device as claimed in  claim 5 , in which said synchronization system has a first wheel in one of said two rows of wheels and a second wheel in the other of said two rows of wheels, said first wheel being in contact with said second wheel, and wherein said first wheel has a hardness which is slightly greater than the hardness of said second wheel. 
     
     
       10. A postal sorting machine comprising a destacker of flat objects and a device for conveying flat objects in series and edge-on, in which said flat objects are moved in a conveying direction while at the same time being separated each from the next by a spacing which is normally constant, which device further comprises a synchronization system capable of compensating for any variations in spacing between two consecutive objects, this system comprising two parallel rows of driven wheels made of elastically deformable elastomer and between which each object is gripped and moved in said conveying direction, each wheel having a rotation spindle, the position of which is fixed, the wheels being rotated by a motorization system which is controlled to accelerate and/or retard the movement of each object between the two rows of wheels on the basis of a detection as to whether the front edge of the object has been early or late in passing a determined position upstream of the two rows of wheels, compared with a time reference which indicates the spacing between objects, said destacker having an exit and said conveying device being arranged in the continuation of the destacker exit, the destacker comprising a destacking plate on which the first object of a stack of objects that are to be sent out in sequence rests before being ejected at the exit of the destacker, this plate being arranged in a vertical plane parallel to said direction of conveying between the two rows of wheels and offset from said direction by a distance which corresponds to half the maximum thickness of an object. 
     
     
       11. A postal sorting machine as claimed in  claim 10 , in which the conveying device comprises two twin wheels on each fixed-position rotation spindle, the wheels of the two rows of wheels located upstream in the direction of conveying extending over a shorter height than the wheels located downstream. 
     
     
       12. A postal sorting machine as claimed in  claim 10 , in which the conveying device comprises a first sensor disposed close to the upstream wheels of the two rows of wheels in the conveying direction and arranged to detect the passage of the front edge of each flat object, and a second sensor disposed close to the downstream wheels of the two rows of wheels in the conveying direction and arranged to detect the passage of the rear edge of each flat object, and in which, in response to detection by the first sensor, the motorization system is controlled to accelerate and/or retard the movement of the flat object between the two rows of wheels to a certain conveying speed and in which, in response to detection by the second sensor, the motorization system is controlled to pick up a subsequent object between the two rows of wheels at a certain speed which is lower than said conveying speed, and in which if first said sensor detects the passage of the front edge of a flat object which is delayed with respect to said time reference, the motorization system is controlled to accelerate and then retard the movement of the flat object between the two rows of wheels until said certain conveying speed is reached. 
     
     
       13. A postal sorting machine as claimed in  claim 10 , in which the two rows of wheels of the conveying device extend over a length in said conveying direction which is slightly longer than the longest length of a flat object. 
     
     
       14. A postal sorting machine as claimed in  claim 10 , in which each wheel of the conveying device comprises a hub and an annular tread strip connected to the hub by elastically deformable circular arc-shaped fins, the two ends of each fin which are for connecting to the hub and to the annular tread strip of the wheel being disposed along a radius of the wheel. 
     
     
       15. A postal sorting machine as claimed in  claim 10 , in which said synchronization system has a first wheel in one of said two rows of wheels and a second wheel in the other of said two rows of wheels, said first wheel being in contact with said second wheel, and wherein said first wheel has a hardness which is slightly greater than the hardness of said second wheel.